1. Field of the Invention
The present invention relates to a rear projector including an image generator that has an optical device for modulating a light beam irradiated by a light source in accordance with image information to form an optical image and a projection optical system for enlarging and projecting the optical image, a box-shaped casing for accommodating the image generator, and a screen exposed on one of the sides of the box-shaped casing onto which the optical image generated by the image generator is projected.
2. Description of Related Art
Recently, a rear projector has come to be used in the field of home theater etc. Such rear projector has an image generator for generating a projection image, a box-shaped casing accommodating the image generator and a reflection mirror for reflecting the projected image and a transmissive screen exposed to a side of the box-shaped casing.
The image generator has a light source lamp, an optical device such as a liquid crystal panel for modulating a light beam irradiated by the light source lamp in accordance with image information, and a projection optical system such as a projection lens for enlarging and projecting the generated optical image.
The optical image generated by the image generator is reflected on a mirror etc. to be projected on the transmissive screen, which transmits through the screen to be viewed as an image.
Such rear projector also accommodates acoustic device such as a speaker inside the casing thereof, so that the large-screen image has much presence with the use of the acoustic device.
Incidentally, the image generator of such rear projector has the light source lamp, a light source driving block for driving the light source lamp, and a power source block for supplying electric power to the board for controlling the drive of the optical device, all of which are heat source. On the other hand, some of the components of the optical device etc. are weak against heat. Accordingly, it is important to cool the interior of the projector efficiently.
Conventionally, the interior of the projector is conducted according to the following arrangements.
In an arrangement shown in Japanese Patent Laid-Open Publication No. 2001-343708, an intake opening and an exhaust opening are provided on a front side, i.e. on a side provided with a screen, of the casing of a rear projector, through which the cooling air is introduced to the interior of the projector and is exhausted therefrom (see FIG. 6 thereof).
In another arrangement shown in Japanese Patent Laid-Open Publication No. Hie 9-98360, an intake opening is provided on a front side of the casing of a rear projector and an exhaust opening is provided on a rear side of the casing of the rear projector, where the interior of the projector is cooled by a cooling channel from the front side to the rear side of the rear projector (see FIG. 9).
However, according to the cooling method shown in Japanese Patent Laid-Open Publication No. 2001-343708, since both of the intake opening and the exhaust opening are provided on the front side of the casing, a part of the air having cooled the interior of the projector and exhausted from the exhaust opening is taken in by the intake opening, thus raising the temperature of the cooling air introduced from the intake opening and the interior of the projector cannot be efficiently cooled.
Further, since the heated air having cooled the interior of the projector is exhausted from the front side of the casing, the spectator may feel unpleasantness according to the amount of the discharged air.
Since the exhaust opening is provided on the rear side of the casing in the cooling method shown in Japanese Patent Laid-Open Publication No. Hie 9-98360, when the rear projector is installed, for example, with the rear side thereof being opposed to a room wall, the flow of the cooling air is blocked by the wall, so that the heat may remain interior the projector and the interior of the projector cannot be efficiently cooled.
An object of the present invention is to provide a rear projector capable of efficiently cooling the interior of the projector and giving no unpleasant feeling to the spectators.
A rear projector according to an aspect of the present invention comprises: an image generator having an optical device that modulates a light beam irradiated by a light source in accordance with image information to form an optical image and a projection optical system that enlarges and projects the optical image; a box-shaped casing that accommodates the image generator; and a screen exposed on any one of lateral sides of the box-shaped casing that on which the optical image formed by the image generator is projected, in which an intake opening that introduces a cooling air to the image generator is formed on a first lateral side of the casing adjacent to a first edge of the screen other than the lateral side provided with the screen and an exhaust opening that discharges the air after cooling the image generator is formed on a second lateral side of the casing adjacent to a second edge of the screen opposite to the first edge of the screen, and in which a cooling channel for the cooling air to be flowed is formed inside the casing along the surface of the screen.
The optical device as a component of the image generator includes various optical modulators capable of optically modulating the light beam irradiated by the light source in accordance with image information, which may modulate the color image with a single plate or, alternatively, may combine a plurality of color lights of R, G and B by a color combining optical device such as a prism to form a color image after modulating the color lights with a plurality of optical modulators. The optical modulator includes a micro-mirror as well as transmissive liquid crystal panel and reflective liquid crystal panel.
The shape of the screen is not restricted, but may be designed in any manner such as rectangle and trapezoid.
According to the above arrangement, since the intake opening and exhaust opening are separately formed on the lateral sides other than the side provided with the screen adjacently to the opposing edges of the screen, the air having cooled the interior of the projector discharged from the exhaust opening can be securely prevented from entering into the intake opening. Accordingly, the temperature of the air introduced from the intake opening is always approximately the same as room temperature, thereby efficiently cooling the interior of the casing.
Further, when the rear projector is installed with backside thereof facing, for instance, a wall of a room, the flow of the cooling air is not hindered by the wall, thereby efficiently cooling the interior of the projector.
Since the air having cooled the interior of the projector is discharged from the lateral side of the casing provided with no screen, the air having cooled the interior of the projector is not discharged from the front side of the casing, thus causing no unpleasant feeling on spectators. Further, blur of image on the screen caused when the temperature of the discharged air is high can be prevented.
In the above rear projector, a first duct that guides at least a part of the cooling air in normal line direction of the surface of the screen may preferably be provided in the cooling channel.
The first duct may preferably have a tube-shaped body having an introduction hole that introduces at least a part of the cooling air at a side adjacent to a first end thereof and a discharge hole for discharging the introduced cooling air at a side adjacent to a second end opposite to the first end. Incidentally, the cross section of the first duct may be designed in any manner such as cylindrical shape and square pillar in accordance with layout of the interior of the projector and the component to be cooled as long as the cooling air can be efficiently flowed.
According to the above arrangement, when it is preferable to form a cooling channel in a normal line direction of the screen surface according to layout of the components of the image generator, the cooling air can be guided in the normal line direction by the first duct, thus further efficiently cooling the interior of the projector.
Further, since the introduction hole and the discharge hole of the first duct are formed as described above, the air flowing along the screen surface can be taken in at the introduction hole and can be discharged from the discharge hole again in a direction along the screen surface, the entire flow of the cooling channel inside the projector is not impaired, thus efficiently cooling the interior of the projector.
In the above-described rear projector, the first duct may preferably form a channel for cooling the light source and may preferably be directly connected to the exhaust opening.
Since the first duct forms the channel for cooling the light source and is directly connected to the exhaust opening, the air with the highest temperature after cooling the light source is directly discharged from the exhaust opening, so that the air having cooled the light source is not fed to the other part of the image generator, thus enhancing cooling efficiency.
In the above-described rear projector, the image generator may preferably have a first power source block that supplies electric power to a controller that controls the drive of the optical device, a sound signal amplifier that amplifies a sound signal annexed to the image information and a second power source block that supplies electric power to the sound signal amplifier, and a partition that divides a cooling channel of the first power source block from a cooling channel of the sound signal amplifier and the second power source block may preferably be provided in the cooling channel.
According to the above arrangement, the air flowing through both cooling channels can be divided by the partition. The temperature of the air after cooling the first power source block is relatively low and can be used for cooling the sound signal amplifier and the second power source block. Accordingly, the components of the image generator can be cooled without loss, thus enhancing the cooling efficiency.
The above rear projector may preferably have a leg provided on the lower side of the casing that supports a body of the projector, in which a second duct that introduces a part of the cooling air to the lower side of the projector is provided to the intake opening, and in which an optical device cooling channel connected to the second duct to guide the cooling air to the optical device is formed on the lower side of the casing and the leg.
The leg may preferably comprise a receiver surface abutted to the entire lower side of the casing, an external rib surrounding the outer circumference of the receiver surface so that the casing is fitted, a support formed on the opposite side of the external rib to surround the opposite side of the receiver surface and a leg body including a matrix-shaped reinforcing rib formed within the support.
The optical device cooling channel can be formed by covering a concave groove formed on a part of the receiver surface with the lower side of the casing.
According to the above arrangement, since the cooling air introduced from the intake opening is directly supplied to the optical device by the optical device cooling channel, the cooling air of low temperature can be introduced to the optical device to enhance the cooling efficiency of the optical device.
Since the optical device cooling channel is provided between the lower side of the casing and the leg, the layout of the image generator is not restricted, thus enhancing the freedom of design.
Further, since the optical device cooling channel can be formed only by providing the concave groove on the receiver surface of the leg, thereby simplifying the structure.
A fan that cools the first power source block may preferably be provided adjacent to the first power source block and a fan that cools the light source may preferably be provided adjacent to the light source, the fans sharing the cooling air introduced from the intake opening to form two cooling channels.
According to the above arrangement, since the air introduced from the intake opening is divided to the channel for cooling the light source and the cooling channel for the two power source blocks, the hot air after cooling the light source does not affect on the two power source blocks, thus efficiently cooling the light source and the power source block.
In the above rear projector, the casing may preferably have a first casing that accommodates the image generator and a second casing provided with the screen, and the dimension of the first casing along the screen surface may preferably be smaller than the dimension of the second casing along the screen surface.
According to the above arrangement, even when the rear projector is installed closely adjacent to wall of a corner of a room etc., the cooling air can be flowed in the direction of both lateral sides of the first casing through the space on the side of the first casing formed by the dimension difference of the vertically disposed second casing and the first casing, thereby efficiently utilizing the space of a room etc.
In the above rear projector, the intake opening may preferably have at least two intake systems that introduce the cooling air into the interior of the casing, and the exhaust opening may preferably have at least two exhaust systems that discharge the air after cooling the interior of the casing.
According to the above arrangement, since more than one intake system and exhaust system are provided, the components can be cooled in more local manner, thus enhancing entire cooling efficiency. Further, since two or more cooling channels are provided, hot component and a part not so hot but required to be cooled can be cooled with separate cooling systems, thus enhancing cooling efficiency.
In the above, a dust filter may preferably be provided at least one of the intake systems.
According to the above arrangement, the invasion of dust into the interior of the casing can be prevented by the dust filter such as an air filter, thus preventing malfunction of the image generator and improving the quality of the projected image.
In the above rear projector, the screen may preferably be formed in a rectangle.
According to the above arrangement, since the screen is formed in a rectangle, the intake opening and the exhaust opening formed on respective sides of the casing adjacent to the opposing edges of the screen can be located in an opposing manner. Accordingly, the cooling air can be flowed substantially in one direction from the intake opening to the exhaust opening, so that the hot air can be kept from staying inside the rear projector and cooling efficiency can be enhanced.